Telephone-exchange system



Patented Apr. 20, 1920.

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S. B. WILLIAMS, In.

TVELEPHONE'EXCHANGE SYSTEM.

APPLICATIN FILED MMI. 29, I9I- I l 1,337,681 Patented Apr. 20, 1920.

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S. B. WILLIAMS, 1R.

TELEPHONE EXCHANGE SYSTEM.

AFPLICAIION FILED MAR. 29,1911.

S. B. WILLIAMS, 5R.

TELEPHGNE EXCHANGE SYSTEM.

APPUCAHON HLED MAn.29,19|.

1,337,681 Patented Apr. 20, 1920.l

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//1 Ven/0n 500706/ 5 M//Y//a/Ws J/f STATES PATENT oserais-.f

SAMUEL". B. WILLIAMS, JB., F BROOKLYN, NEW YORK, ASSIGNOB TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

i TELEPHONE-ExeHANGESYSTEM.

Specification of Letters Patent.

Patented Apr. 20, 1920.

Application tiled March 29, 1917. Serial No. 158,231.

' at Brooklyn, in the county of vKings and State of New York, have invented certain new and useful Improvements in Telephone- Exchan e Systems, of which the following is a full clear, concise, and exact description.

This invention relates to telephone ex change systems, and more particularly to call distributing systems employing line finder switches. 5

T t is the object of this invention to provide a system in which power-driven switches may be used, and in 'which line finder switches are arranged to be controlled `in group, subgroup and line selection.

A further object of this invention is to provide a call distributing system in which an operators position is made non-selectable when a certain amount of work is stored u'p at such position.

It is an additional object of this invention to provide a call distributing system in which the calling lines'may terminate in various sections of a Contact bank, the arrangement being such that when a call is initiated an `idle operatorls position l1s se-V lected, 'whereupon an allotted finder arranged to extend the calling line to said selected operators position may be started in search of the calling line, means being necessarily present to control the starting otra finder" which has access to the proper section of the panel bank.

Affeature of the'invention is an arrangement in which line finder switches of the panel type accomplish group and subgroup finding, in accordance with registrations set u in response to the electrical oontions ofthe group and subgroup' relays individual to the group and subgroup in which the calling subscribers line is located.

An additional feature of; the invention is an arrangement by which counting relays are actuated at an operators position in response to the calls incoming to such position as long as'it is selectable. l

A further feature of the` invention is an arrangement by which an operatorls position is rendered non-selectable whenshe has two calls stored up at her tion also being non-selecta le if she has one Ashows calling subscribers lines wit ition, the posiy call stored up and is listening in on another call. i

It is thought that the invention will best be understood from the following detailed description, reference being had to the aocompanying drawings.

Referring now to the drawings, Fi ure 1 the group and sub-.group relays common to certain ones of suc lines:J Fig. 2 shows the circuits of a line finder switch and a connectingV operators cord circuit; Fig. 3 shows controlling circuits for settingthe line finder switch of Fig. 2 andthe relays by means of which anioperators position may be selee-ted, together Vwith an allotter tswitch which determines which one of a plurality of line finders shall be started after a position has been selected; Fig. 4 shows duplicate apparatus at two operators positions, and illustrates the arrangement by which starting circuits-from the various sections may put into operation the desired apparatus at` a selectable operators position.

A,In Fig.`3 the sequence switch contacts shown within the dotted lines in the lower left-hand portion of the drawing are controlled by the sequence switch 200 associated with them, the remaini sequence switch contacts shown in this y re being controlled by an allotting sequence switch 300.

\ The sequence switch contacts shownin Fig.

2 are controlled by the line finder sequence switch 400. Y

The general arrangement of the system isl as follows. vIf we assume that there are twent -we hundred calling lines to be serve( by the operators and that these calls are to be extended to such operators' by Vmeansof line finder switches each having a capacityg of five hundred lines, the lines will be arraned in five sections of panel bank, `each of ve hundred lines ca acity. There will be Va plurality .of line nders serving each section of the panel bank and their arrangement must be such that a calling line may be extended to any operators position.

' Therefore, the line finders, associated" with proper section of panel bank will be started to extend the call to the selected operators position.

Each section of tire hundred lines is divided into live main groupsot' one hundred lines each which may he selected in response to the brush selecting operation of the line finder switch. Each group of one hundred lines is 'divided into tour sub-groups ot' twenty-five lines each. The sub-group of twenty-tive lines is selected-in response to the group selecting movement of the line finder switch, and the indiridual terminal set in the selected group is selected by a simple hunting lnoiement.

In Fig. 1 are shown the lines ot t'our calling subscribers. 0f the substatious indicated, 1 and 2 belong to the same main roup of the one hundred lines, which has geen shown as the first main group. while, the substations 3 and L belong to another main group of one hundred lines uhiclrhas been shown as the, fifth main group. Stations 1 and. however. both belong to corresponding slib-groups of their respective main groups, and therefore their slib-group relays control a common point'on the recording apparatus shown in Fig. Similarly, substations 2 and i are located in corresponding sub-groups of their respective. main groups and therefore control another common point on the recording apparatusI shown in Fig. 3.

Assuming that the. subscriber at substation 1 desires to make a call he will remore his receiver from the hook, whereupon linc relay 5 will be energized over a circuit from grounded battery. left-hand Winding ot' line. relay 5, outer lett-hand armature and back contact of cut-ott relay G thc loop ofthe calling line. the inner armature and back contact of cut-off relay 6, right-hand winding of relay 5, to ground. Relay 5 upon energization completes a circuit from grounded battery,` armature and back contact ot relay T. upper right-hand armature and back contact of relay 8, conta-ct QVarInature and front contact of relay 5. to ground. Contact 9 is controlled by a sequence switch 100. there -being one of these sequence switches associated with each sub-group ot' calling lines for a purpose to be hereinafter described. Relay 8 ,is energized in the above traced circuit and locks up over a path from grounded battery. winding of relay T, lou'er right-hand armature and back Contact of relay 8 (corresponding to relay 8). lower ri lit-hand armatures and back contacts ot' oter relays of the main V roup corresponding to relay 8, ri lit-han( armatures of r lay 8, Win ing o relay 8 contact 9, armature and front contact of relay 5, to round. It is thus obvious that only onefca-l may he initiated in a main group at a tlme, since, if any relay corresponding to 8 is energized',

ot' relay 1l. lower right-hand armature and back contact of relay 10 (corresponding lo relay 10). lower right-hand armatures and back contacts ot' other relays corresponding to relay l0. there heilig one such relay for cach main group, conductor 153i. thc righthand armatures of relay 10 in an actuated condition. winding ot' relay lll. armature and t'ront contact of rel-.1y 7. to grounded battery. Relay ll is energized in this circuit and prevents the energiz'ation ot' any other main Orou i relay corres iondino' to 1U. since. erat its upper arn'lature 1t opens the circuit over which all such` relays are initially cnergized. The energization of rel-.1y l1 completed a circuit from grounded battery. winding of relay 2S. lett-hand armature and front contact of relay 10. the lower armature and front contact of relay 11. to ground. Relay 29 is thereupon energized over a circuit from grounded battery. Winding of relay 29.vleft-hand armature and front contact of relay S. to ground at the left-hand armature and front contact of relay Q8. The energization ot' relay 29 supplies ground at its right-hand armature and t'ront contact for operatingl the sub-group will be subsequently described.

The energization of relay 11 also comi pletes a Circuit from ground. lou'erarmature and hack contact of relay 12. upper armature and front contact of relay l1. conductor 14, winding of relay V15. to grounded battery. Relay 'l5 is energized. whereupon a circuit is completed from grounded battery. lower arm-.dure l* contact of relay 16, upper right-h vregis(ering apparatus shown in Fig. 3. as

nture and back contact of relay Y ing of relay 17. armature and back c ntiict of relay 1S. armature and front Contact of relay 18. armature and t'ront contact of relay 15. to conductor 14, and ground. This starting circuit is extended Jfrom groundv through the armatures' and front contacts of relays 18 associated `with busy operators` positions which are in a nonselectable con dition` and the call is extended to the first position at which a relay. in this case as-. sumed to be the relay 18, is in a nonfactuated condition to indicate the nonhusy condition of the peretors position.

Relay 17 upon energization locks up in a circuit from grounded battery, winding of relay 1G, the lower right-hand armatures and back contacts of section-selecting relay 17 corresponding to relay 17, conductor 20, the right-hand armatureof relay 1l' in an actuated condition, and the Winding of relay 1T to ground over the path described.

It is to be understood that there is a starting circuit similar to the one described associated with each tive hundred line section of finders. and that there are position selecting relays corresponding to relays 18 and 18 associated with each such starter circuit. As shown in Figs. and 4, the starting circuits ot' three sections have been indicated at two operators positions. It is obvious that while one of the relays 17 is energized, it will be impossible to energize another corresponding relay due to the actuated condition of the common relay 16.

The registering and sending equipment indicated within the dotted line in the lower left-hand portion of Fig. El is associated with the allotter switch 300. lt will be understood that there are at each operator`s` position many allotting sequence switches as there are sections of a contact bank. and

that a sending equipment similar to that indicated in the lower left-hand portion of Fig. 3 is permanently associated with each such allotter.

It will be seen therefore that by means of the relaysl an idle position mayibe lected. In response to the selection of an operators position. a relay corresponding to relay 17 will be energized to controlthe starting of an allotter finder. The finders serving each section of panel contact bank are divided into groups. .there being as many groups as there are operatorspositions. Therefore. the particular relay 1T which was energized will determine in which sec tion of contact bank and in which group of finders an allotted finden-.will be started.

In case all the operators positions are busy, a circuit will be completed from grounded battery. winding of relay 21. front contact and armature of relay 18, which has been shown as the last in the chain. through the front contacts and armatures ot' position selecting relays corresponding to relays 18 and 18. front contact and armature of relay 15. to gro-und over the path described. The energization of relay 2l completes a circuit for lamp 22 from grounded battery. lamp 22, armature and front contact oi' relay 21 to ground. The lighting of this lainp will enable a count to be made of the` number of tim-es theV busy condition of all operators positions arises.

Relay 1.7 upon energization completed a lcircuit from grounded battery. winding of relay 23, left-hand armature and front contact of relay 17 to ground. A circuit is then completed from grounded battery, power magnet of sequenceswitch 400, contact 5102, conductor 403, allotter contact 302, upper armature and front contact of relay 23 to ground, for moving the sequence switch 400 out of position 1 into po ition 2 under the control of its normal spri g 401.

Then sequence switch 400 arrives in position 2, a circuit is completed from grounded battery, power magnet of sequence switch 200. contact 202. conductor 24, allotter contact 303, conductor 304, contact 404. to ground, for moving this sequence switch out of position 1 and into position 3, under the control of its master contact 201. Vhile sequence switch 200 was passing through positions l `to 2, a circuit was completed from grounded battery, Winding of relay 27. contacts 204 and 205, conductor 206 to ground at the right-hand armature and front contact of relay 29. The relay 27 is energized to control the sub-group selection in `a manner to be subsequently described.

Then sequence switch 200 arrived in position 3. a circuit was completed from grounded battery. winding of relay 2G, lefthand armature and back contact of relay 36, contact 20T. conductor 208, to ground atfthe left-hand armature and front contact of relay 2S. Relay 26 is energized in this circuit and prevents the further' advance of sequence switch 200. If the call had been originated in some other main group, for instance. the main group including the sub scribers whose substations are indicated at 3 and 4, sequence switch 200 would have been moved out of position .3 over a circuit from grounded battery, power magnet of sequence switch 200, contact 203. conductor 25, -allotter contact conductor 306, con- 105 tacts 4,05 and 1:00. conductor 40T. allotter contact 30T, right-hand armature and back contact of relay 26. and would have advanced into a position determined by which one of the main group relays corresponding 110 to relay 28V had been energized. For instance. if relay 28 had been energized. the sequence switch 200.y would have advanced into position 7. since relay 26 would not have been energized to break the above 115 traced circuit until sequence switch 200 arrived in position 7. In this case the energizing circuit of relay 26 would have been extended from grounded battery. winding of relay 26. left-hand armature and back 120 contact of relay 30. contact 209. conductor 210. left-hand armature and front contact of relay 2S. to ground.

vThe switch 200 operates both Vas a registeil and as a sender. its sending function be- 125 ing accomplished on the complement basis. that is. it will move to an end position in every case and it the fifth brushis to be selected. it will be stopped .in an early position so that five impulses will be sent to 130 the line finder switch during brush selection. However, if the first brush is to be selected, the switch 200 will be stopped in a position ljust before its end posltion and thus only one impulse will be sent.

lVhen relay 26 is energized, a circuit is completed from grounded battery, power magnet of sequence switch 40H, contact 408, conductor 409, allotter contact 310, contact 210, armature and front contact of relay 2U, to ground, for moving sequence switclr 400 out of position 2 and into position lVith sequence switch 100 in position 3, a circuit is completed from grounded battery, winding of relay 12, conductor 31, allotter Contact 308, conductor 309, Contact 410, to ground. Relay 12 is energized and at its lower armature removes ground from a starter wire 14, whereupon relays`15, 1T and 16 are denergized. The unactuated condition of relay 16 will now permit another call from the same or some other section to be extended to the selecting relays 17 corresponding to relay 17.

Relay 12 at its lower armature also rcmoved ground from the windings of relays 10 and 11, causing their denergization. Relay 1() causes in turn the denergization of relay 28, but this relay being slow to release. maintains its armatures attracted for a sufficient period of time for a circuit to he completed from grounded battery, winding of a timing sequence switch 100, contact 102, left-hand armature and front contact of relay 29, right-hand armature and front contact of relay 28, lower armature and front contact of relay 12, to ground. The timing sequence switch 100 is then moved out of position 1 and moves through a complete cycle of rotation under the control of its master contact 101. holding open at its contacts 9 the circuits of sub-group relays corresponding to relay 8, and thus prevents the sub-group from starting other line finders for a time interval of sufficient length to permit the selection` of the topmost line of any multiple bank. All succeeding calls in the sufi-group are held up during this time interval.

With the relay `12 energized. a circuit is also completed from grounded battery, power magnet of sequence switch 400. contact 411, conductor 412. allotter contact 311. conductor 312, upper armature and front contact of relay 12, conductor 31. allotter contact 308, conductor 309,-contact 410. to ground, for moving this sequence switch out of position 3 and into position 4.

With sequence switch 400 in position 4, the fundamental circuit is completed from grounded battery, Winding of relay 32, contacts 413, 414, conductor 415, allotter contact 313, winding of stepping relay 33, contact 211 to ground. Relays 32 and 33 are energized in this circuit, relay 32 completmausi contact 41T, left-hand armature and front ,Contact of relay 32, to ground. Magnet 3.4, upon energization, presses the driving ribbon 35 into engagement with a roller 36 constantly rotating in the direction indicated by the arrow, and causes the elevation of a brush shaft 37 carrying a plurality of brush sets, similar to the one indicated at 38, in an upward direction.

The mechanical structure of the switch shown in Fig. 2 is somewhat similar to the structure of the switch shown in Patent No. 1,123,696. issued to E. B. Craft and J. N. Reynolds, and is of the type in which a plurality of normally inoperative brush sets are mounted on a ln'ush-carrying shaft, the shaft heing arranged to be advanced into a position wherein a desired brush set may be rendered operative, after which such operated brush set may be advanced in a groupselecting movementand subsequently in a line-selecting movement.

Yhcn sequence switch 40() arrived in position 4, a circuit was completed for relay -30 from grounded battery, winding of relay 30, allotter contact '314, conductor 315. contact 418, to ground, and this relay locked up over a path from grounded battery, winding of relay 30, right-hand armature and front contact of such relay, contact 212, to ground. 'v Vhen stepping relay was first ener gized, a circuit was completed from grounded battery, winding of relay 26, left-hand armature and front contact of relay 30, contacts 213 and 214, right-hand armature and back contact of relay 39, armature and front contact of stepping relay 33 to ground. Relay 26 was energized in this circuit and completed a circuit from grounded battery, power magnet of sequence switch 200. contact 203, conductor 25. allotter contact 305, conductor 30G, contacts 405 and 419, closed in position 5 of sequence switch 400, conductor 409, allotter contact 310, contact 210, armature and front contact of relay 26. to ground, for moving this sequence switch out of position 3 and into position 4.

vWhen commutator brush 40 engages the first conducting segment of a commutator 41, a circuit in shunt of the fundamental circuit is completed from grounded battery, winding of relay 32, right-hand armature. and front contact of relay 32, conductor 50,

contact 420, conducting segment of commutator 41, brush 40, to ground Stepping relay 33 is shuntedvout by this circuit and de-4 travels over commutator 41 must be such that the sequence` switch will arrive at a V stopping position a morent after the brush engages the conducting vsegment of the commutator. 'lnerefore, when'the commutator .brush 40 moves onto the next insulating segment of the commutator, relay 33 will be again energized and will complete a circuit for relay 26, causing sequence switch 200 to be moved out ofposition 4 and into position 5. y

`When sequence switch 200 leaves position 7, at which time the brush shaft 37 will have been advanced five steps, the lower branch of the fundamental circuit' is broken at contact. 211, and when a moment later brush 40 engages an insulatingsegment of commutator 41, the upperY branch of the locking circuit of relay 32 is opened and this relay denergizes, opening at its left-hand armature the circuit of the driving magnet 34 and bringing the brush shaft to rest 1n a osition ,wherein the fifth set of brushes may e tripped upon the operation of the trip magnet 43. he sequence switch 200 comes to rest in position 9.

The denergizationpf relay 32 completed a circuit from grounded battery, power magnet of sequence switch 400, contact 421, left-hand armature and back contact of relay 32, to ground, for moving this sequence switch out of position 5 and lnto position 6. In positions 6 and 7 a trip magnet 43 is energized over a circuit from grounded battery, winding of magnet 43, contact 422, to ground. The energization of the trip magnet places a projtlon in the path of a positioned set of. brushes so that upon subsequent upward 'movement, the desired brush set will be released.

It will be remembered that of the sub group selection-controlling relays 27, 44, 45V

` plished, and since the calling line is located,

as in the present case, in the fourth group, the sequence switch will not be moved out of position 9. If, however, the call had orginated in the second sub-group, the relay 45 would have been energized and would have locked up to ground at contact 216. In this case sequence switch 200 would have been moved out of position 9 and into position 11 so that two impulses would be sent instead of four, as in the present case. In this case, in position 9 of sequence switch 200, relay 39 would have been energized over a circuit from grounded battery, winding of relay 39, contact 217, right-hand `armature'and back contact of relay 27, to

ground. The energization of relay 39 would thenhave completed a circuit from grounded battery, power magnet of sequence switch 200, contact 218, left-hand armature and front contact or relay 39,

to ground, for moving lthis sequence switch out of position 9 and into position 10. Relay 39 would have denergized while sequence switch 200 was passing from position 9 to position 10, but would have again been energized in position 10 of sequence switch 20() over a circuit from grounded battery, winding of relay 39, contact 219, ri lit-hand armatures and back contacts of relzays 44 and 27, to ground, and would `have completed the previously traced circuit for moving sequence switch 200 out 4of position 10 into position 11.

As stated, in the present case, sequence switch 200 remains in position 9 until moved out of position 9 under the control of stepping relay 33, upon the reestablishment of the fundamental circuit.-

Whensequence switch 40() arrives in position 6, the fundamental circuit is reestablished and extends from grounded battery,

winding of relay 32, contacts 413, 414, conductor 415, allotter contact 313, winding of stepping relay 33, contact 220, right-hand armature-and front contact of relay 27, to ground; Relays 32 and 33 are energized in`this circuit. Relay 32 locks up .as before and at its left-hand armature completes a circuit'from grounded battery, power magnet of sequence switch 400, contact 416, left-hand armature and frontcontactof relay 32, to ground, for movin this sequence switch out of position 6 an into position 7 In Yposition 7 of sequence switch 400, a circuit is completed from grounded battery, -windin of 11p-drive magnet- 47, contact 423, le -hand armature and frontcontact of reldy 32v to ground. The ener 'zation of magnet 47 presses the driving ri bon 35 against the high-speed rollerl 48Vconstantly rotating yin the `v`direction indicated by the arrow, and causes 4the brush shaft 37 to be .elevated in a group-selecting movement.

`Relay 26 was energized in position 9 of Sequence switch 200 over a circuit from grounded battery, winding of relay 26,

left-hand armature and front contact of relay 30, contacts 213 'and 214. right-hand armature and back contact of relay 39, t0 ground at the armature and front Contact of stepping relay 33, when this relay was energized upon the closure of the fnndamental circuit.

In position 7 of sequence switch 100. and with relay 26 energized, a circuit is completed from grounded battery. power magnet of sequence switch Q00, contact4 Q21. allotter Contact 316, conductor 31T. contacts 454 and 419, conductor 109. alloter Contact 310, contact 210. armature and front contact of relay 26 to ground. for moving this sequence switch out of position 9 and into position 10.

'hen commutator brush 4l) engages the first conducting segment of the coinmutator 49. a circuit in shunt of the fundamental circuit is completed from grounded battery. winding f relay 32, right-hand armature and front contact of relay yconductor 50. contact`425. conducting segment. of commutator 49. brush 40, to ground. Stepping relay 33 is shunted ont in this circuit and deenergizes, causing in turn the denergization of relay 26. The driving circuit of sequence switch 200. which is again operating as a sender, is thus opened at the armature; of relay 2G, and this sequence switch comes to rest in position 10. The timing of the sequence switch 200, with relation to the speed at which the commutator brush 40 travels over comniutator 49. must be the same as in the preceding case. that is. such that the sequence switch will arrive at a stopping position a moment a tter the comniutator brush engages a conducting segment of the oonnnutator. Therefore. when the commutator brush 4() moves onto thc next insulating segment of commutator 49. relay 33 will be again energized and will complete a circuit for relay '26 to move, the sequence switch 200 ont of position 10 and into position 11.

Then sequence switch 200 leaves position 12. at which time the brush .shaft 3T will have been advanced four steps. the lower branch of the fundamental circuit is broken at contact 220 and when. a moment later. brush 40 engages an insulating segment of commutator 19. the upper branch of the locking circuit ot relay 3:2 is opened and this relay deiinergizes. opening at its let'tv hand armature the circuit of the driving magnet 4T and bringing the brush shat't to rest with the tit'th set of brushes in a position below `the fourth sub-group ot' terminais. The sequence switch 21N). on leaving position l2. completes its cyclc oiE rotation and comes to rest in position 1. (ln leaving position 12. the locked-up relays Si() and L arc dciincrgizcd. lea ying the registering and sending apparatus in a condition t'or reoperation. The denergization of relay 32 completed a circuit from grounded battery, power magnet of sequence switch lut), contact 421. and the armature and back contact ot relay 3:2. for moving` this sequence switch out ot' position T and into position S. In position t5 ot sequence switch 400. relay 32 is vagain energized over a circuit from grounded battery. winding of relay 3;). contact 413. contact 426, armature and back contact ot' relay 51. to ground. and locks` up through its right-hand armature. At its lett-hand armature` a circuit' is completed from grounded battery. power magnet ot' sequence switch 400. contact liti. lett-hand armature and t'ront contact of relay 22 to ground.` t'or moving this sequence switch out of position H and into position t).

In position il ot sequence switch 400. a circuit is completed vfrom grounded battery. winding ot' up-drive magnet 4T. contact 123. left-hand armature and front contact ot' relay 32. Magnet 4T is energized to Cause the upward motion of brush shat't 3T. to cause thc selected brush set to hunt t'or thc 'alling line in the selected sub-group. 'hen the brush set 3S. composed of the brushes 151. 52 and 523. engages the terminals` ot the calling line. relay 5t will beieiwrgized over a circuit from grounded battery. winding ot` relay 54. contact 42S( test brush 151. test terminal 55. and the winding ot' a cntoll relay ti. to ground. Relay 5l. upon its energization. completes an energizing circuit for relay 51 through contacts 42H and 430. and the closed loop ot' the calling substation line. Relay 51 upon energization will open one branch ot' the locking circuit ot' relay 32. Relay 32 is maintained cncr gized. however. a moment longer over a path `extending through contact 431 and a conducting segment oiE comnmtator ou and brush 5T. to ground. until brush .3T engages an insulating segment of connnutator 5G. at which time the brush set will he iiccuratel)| centered on the terminals ot' the calling line. Relay 32 then deenergizes and at its let'thand armature opens the circuit ot' up-drivc magnet 4T. bringing the brush Iset to rest on the terminals ot' the calling line.

l lVhile the brush set was passing over the terminals ot' busy lines. relay 54 could not bc energized. due to the reduced ground potential on the test terminals 5f ot such lines. 'hen the brush set engaged terminals ot' non-calling lilies. relay 5t was encrgizcd. hut relay 51 could not be energized. since the line loop through thc substation was open. duc to the non-calling condition ot' such line.

Relay 32. upon"deiinergizalion. also com pletcs a circuit from grounded battcrv. power inagnct ol' sequence switch VJAHL con-r tact 121. lcl't-hand armature and back contact ot' relay 3:3 to ground7 l'or moving this sequence svvitch out of position 9 and into position 10. In position 10, battery is suplied to test brush 151 and test terminal 55 rom grounded battery, resistance 58, through` of sequence switch 400, contact 435, arma ture and front contact ofl relay 61, righthand armature and back contact of relay 62, to ground, for moving this sequence switch out of position 10 and into position 11.

When sequence switch 400 arrives in position 11, a circuit` is completed from grounded battery, interrupter 63, contact 436, lamp 64, contact 437, to ground. The lamp 64 is caused to flash in this circuit and informs the operator whose position has been selected that a calling line has been connected to the cord. circuitterminating in `'plug 65. VShe thereupon depresses listening key 66 associated with such cord circuit, whereupon a circuit is completed from ground,- vvinding of relay 67, closed contacts of key66, contact 438, and the winding of relay 68, to grounded battery, for energizing relay 68. he listening key 66 was depressed only -momentarily and when it assumes its normal position, a locking circuit for the relay 68 is completed from grounded battery, Winding of relay 68, its right-hand armature and front contact, winding of relay 69, common to all the cords of a osition` closed contacts'of listening-out key 0,common to all `the cords of a position, thrugh the' normal contacts of other listening ke s corresponding to 66, one of which is in icated at 71, through'the normally closed contacts of key 66, and the winding of relay 67, to ground. With relays 68 and 69 energized, a circuit is com leted from grounded attery, windin of re ay 72, Winding of listening-in relay 3, left-handk armature and front contact of relay 68, left-hand armature and front contact of relay 69, to round. Relays 72 and 73 are'energized in t is circuit, relay 72 completing a circuit from grounded battery, power magnet of sequence switch 400, contact 439, outer left-hand armature and front contact of relay 72, to

ground, for moving this sequence switch out of osition 11 and into position 12.

n position 12 of sequence switch 400, a circuit is completed from grounded battery,

line from being seizedby any `68. The. denergization of rela contact 446, lamp 64, inner left-hand armature and front contact of relay 72, to ground,.causing this lamp to burn steadily and indicating to the operator that lier headset has been connected to the calling line The ener'gization of relay 73 causes the operators headset indicated at 74 to be connected to the tip and ring conductors of the cord circuit, and' the operator may enter into tele phonic communication with the calling subscriber in order to ascertain the number of the wanted line. After learning the number of the Wanted line, the operator will depress listening-out key 7 6, causing the denergization of relay 69 and the unlocking of relay 69 causes in turn the denergization of re ays 72 and 73. The de'ergization of relay 73 disconnect's the operators headset from the cord circuit. The denergization of relay 72 causes lamp. 64 to be extinguished.

After learning the number of the Wanted line, the operator will insert plug 65 into a jack 7 6 inwhich the desired line terminates, whereupon a circuit will be com leted from grounded battery, winding o relay 62, sleeve contacts of plug` 65 and jack 76, to ground through the cut-oit relay of the called subscribers line which corres onds to cut-off relay 6 shown in Fig. 1. clay 95 62 and the cut-off relay of the called line are energized in this circuit, the cut-oil relay of the called line operating to remove the control of the called subscribers line relay in the well-known manner.

The operator will then depress a'ringing key 77 to connect ringin current with the line 'of the called subscri er. Upon the release ofthe ringing key and after the called subscriber answers, supervisory relay 78 will 105 be energized in the Well-known manner over thecalled subscribers line.

Upon the termination 'of the conversation and after the calling and called subscribers have replaced their receivers, supervisory relays 60 and 78 are denergized. A circuit is then completed from grounded battery. answering supervisory lamp 779, contact 441, armature and back contact of relay 60, to ground. At the same time the denergization of relay 78 completed a circuit from grounded battery, calling supervisory lamp 80, left-hand armature and front contact of rela 6 2, armature and back contact of relay 8, to ground. The operator is informed 12 by the lighting of these Well-known si nals that connection is no longer desired, w eret upon she removes plg 65 from jack 76, causing the denergization of relay 62. The denergization of relay 60 opened the circuit 125 of relay 61 and this relay denergizes. circuit is then completed from grounded battery, power magnet of sequence switch 400,

. contact 442, armature and back contact of relay 61, right-hand armature and back contery, down-drive magnet 79, contact 443, to

ground. Downdrive magnet 79 is energized and presses driving ribbon 35 into engagement with a roller 80, constantly rotating in the direction indicated by the arrow, and

causes the brush rod 37 to be restored to its lVhen the brush rod arnormal position. rives in its normal position, a circuit is completed from grounded battery, power magnet of sequence switch 400, Contact 444, a normal conducting segment 81, brush 82, to ground, for moving this sequence switch out of position 14 and into its normal position under the control of master contact 401. When the sequence switch 400 leaves position 14, the energizing circuit of magnet 79 is broken at contact 443.

Referring nouT to that point in the operation at which sequence switch 400 arrived in position 8, it will be noted that upon the arrival of sequence switch 400 at position 8, a circuit was completed from grounded battery, winding of relay 83, allotter contact 318, conductor 319, contact 445, to ground. Relay 83 isv energized in this circuit and completes a circuit from grounded battery, power magnet of allotter 300, contact 320. left-hand armature and front contact of relay 83 to ground, for moving this allotter out of position 1 and into a position to allot the next idle finder. `lf when sequence switch 300 arrives in position 3, which is the next allotting position, a circuit is again closed for \relay 83 by way of allotter contact 321, corresponding to contact 445 at the finder switch which is controlled in position 3 of the allotter, the allotter will be advanced out of position 3 in a manner similar to that described and into position 5. lf a finder switch has been restored to normal, but the plug has not been withdrawn from the jack, the finder will still test busy to the allotter, since in this case the circuit of relay 83 will be extended from conductor 319 by Way of conductor 446, to ground. at the right-hand armature and front Contact of relay 62. If all the nders are busy, the allotter 300 will be moved into position 15. in which position it will remain until one of the Endersl arrives in position 1, whereupon a circuit will be completed from grounded battery, power magnet of allotter 300, contact 322, through one of the multiple leads corresponding to 323, a contact corresponding to contact 447 at the finder which has returned to its normal position, to ground. The allotter will then be moved out of posi` tion 15 and into position l. whereupon it will test until the idle finder has been found and allotted for use. lt isto be observed that While the allotter is resting in position 15 a circuit is completed from grounded battery, winding of position-selecting relay 18 associated with the position with which the allotter is associated, and contact 448 to ground. Relay 18 is energized in this eircuit to produce a non-selectable condition at its associated operators position.

When the calling line was first. extended to the operators position by means of starter Wire 14, relay 16 also energized. If, now we assume that at this time the operators position was idle, the energization of relay 16 will complete a circuit from grounded battery, winding of counting relay 84, armature and back contact of counting relay 84', conductor 85, to ground at the upper armature and front contact of relay 16. Relay 8,4 is energized and preparesa circuit for relay 84 so that when relay 16 is de'energized upon the release of the starting circuit when sequence switch 400 arrives in position 3, relay 84 will be energized over a circuit from grounded battery, winding of relay 84, armature and front contact of relay 84, winding of relay 84, and the back contact and armature of relay 86, to ground.

If, before the operator listens in on the iirst call. another call is extended to her position, the second energization of relay 16 will complete a circuit from grounded battery. winding of counting relay 87, the outer left-hand armature and back contact of counting relay 87', the inner lower armature and back contact of relay 67, and the lefthand armature and front contact of counting relay 84', conductor 85, to ground at the upper armature and front contact of relay 16. Relay 87 is energized in this circuit and prepares a circuit for relay 87', so that upon the denergization of relay 16 in response to the release of the starting circuit Which caused its actuation relay 87 Will `be energized in a circuit from grounded battery, winding ot relay S7, armature and front contact-of relay 87, winding of relay 87', armature and back contact of relay 88, to ground. lith the counting relays 84' and 87 energized, a circuit is completed for relay 89 from grounded battery, Winding of relay 89. inner right-hand armature and front contact of relay 37 to g-round. Relay 89 is energized and completes a circuit from grounded battery. Winding of relay 18, coutact 324. conductor 325. left-hand armature and front contact of relay. 89, to ground. Relay 18 is energized in this circuit and attracts its armature to extend the positionselecting starter wire and render the position non-selectable. Therei'mc. no more calls can reach the operators position until some ot the work stored up has been haudied.

When the operator listens in on the first call, the energization of relay 67 completes a circuit from grounded battery, winding of relay 90, right-hand armature and back contact of relay 69, upper armature and front contact of relay 67, to ground. Relay 90 locks up through its left-hand armature and front contact and the inner lefthand armature and front contact of relay 87', and the back contact and armature of relay 88 to ground. W'hen relay 69 is energized in response to the release of the listening-in key which ,has been depressed as previously described, a circuit is completed from grounded battery, winding of relay 88, outer right-hand armature and front contact of relay 87", right-hand armature and front contact of relay 90, left-hand armature and front contact of relay 69, upper armature and front contact of relay 67, to ground. Relay 88 is energized and breaks the circuit of counting relays 87 and 87 and thelocking circuit of relay 90, and these relays deenergize.4 The denergization of relay 90 opens the circuit of relay 88 and it denergizes in turn. lVhile there is one call stored up and the operator is listening in on the first call, the position will still be maintained in a non-selectable condition, due to the energized condition of relay 89, its circuit at this time extending from grounded battery, Winding of relay 89, its right-hand, armature and front contact, to groundat the armature and back contact of rela 86. 4

en the operator depresses another listening-in ke to listen in on the second call, relay 69 wi l Abe denergized as previously described, but relay 67 willbe maintained energized. Therefore relay 90 will be energized over a circuit extending from rounded battery, winding of relay 90, rig t-hand armature and back contact of relay 69, upper armature and front contact of relay 67, to ground. Relay 90 locks up through'its left-hand armature and front contact and the inner left-hand armature and back contact of counting relay 87 and the outer armature and from contact of relay 84 to ground. A s soon then as the second listening key which was de ressed is released, relay 69 is energized and) a circuit is completed from grounded battery, windin of relay 86, outer right-hand armature an back contact of relay 87', right hand armature and front contact of relay 90, right-hand armature and front contact of relay 69, and `the u per armature and front contact of relay 6i, to ground. Relay 86 is energized in this circuit and opens the locking circuits of relays 89, 84 and 84. Relay 84 causes in turn the denergization of relay 90, which causes the denergization of relay 86. It Will thus be seen that as soon as the operator listened in on the second call, relay 89 deenergized allowing relay 18 to denergize in turn and render the position again selectable. It is thus apparent that the operators position 'is non-selectable when two calls have been stored up at her position and remains unselcctable when one call is stored up at her position and she is listening in ou a second call. As soon, however, as she has completed listening in on one of the calls, the position is again rendered selectable.

What is claimed is:

1. In an automatic telephone exchange system, a contact bank, multiple terminals of calling subscribers lines arran ed therein in groups and sub-groups, a ine finder switch 'including a movable shaft carrying a plurality of sets of brushes, there being a `set of brushes for each group of terminals,

said brush sets being normally inoperative with respect to the groups of terminals to which they have access, lneans to advance said brush shaft into a position wherein one of Ysaid brush sets may be rendered operative with respect to the group of terminals served by it, means to advance an operated brush set in a sub-group selecting movement, and means to advance said operated brush set into engagement with the terminals of a calling line.

2. In' an automatic-telepiflexchange system, a contact bank, multiple terminals oi' calling subscribers lines arranged therein in groups and sub-groups, controlling apparatus individual to each of` said groups, cbntrolling apparatus individual to each of said sub-groups, a line finder switch including a movable shaft carrying a plurality of sets of brushes, there being a set of brushes for each group of terminals, said brush sets being normally inoperative with respect to the groups of terminals to which they have access, means to' advance said brush shaft into a position wherein one of said brush sets may be rendered operative with respect to the vgroup of terminals served by it, means to determine the extent of such positioning movement in accordance with the condition of the controlling apparatus individual to the various groups, means to advance said operated brush set in a subgroup selecting movement in accordance with the condition of thc controlling apparatus individual to the various sub-groups, and means to advance said operated brush set into engagement with the terminals of a callin line.

3. n an automatic telephone exchange system, a contact bank, multiple terminals of calling subscribers lines arranged therein in groups and sub-groups, controlling apparatus individual to each of said groups, controlling apparatus individual to each of said sub-groups, registering apparatus, means to position such registering a )paratus in accordance with the group and sub-group designation of the calling line, an automatic switch, means to advance said automatic switch in a group selecting movement in accordance with the setting of a certain one of said registers, means to advance said automatic switch in a group selecting movement directively controlled in accordance with the setting of said registering apparatus, means to advance said automatic switch in a subgroup selecting movement directively controlled in accordance with the setting of said registering apparatus. and means to advance said switch into engagement with the terminals of a calling line in the Selected subgretig.

'-l. n an automatic telephone exchange system, a contact bank, multiple terminals of calling subscriberslilies arranged therein in groups, apparatus individual to each of said groups` a multi-position controlling switch, means 'to advance said controlling switch into a position determined by the group designation of the calling line, an automatic switch, means to advance said automatic switch in a group selecting movement, means to advance said multi-position switch in response to movement of said automatic switch to determine the extent of motion ofsaid switch. and means to advance said automatic switch into engagement with the terminals of a calling line.

5. ln an automatic telephone exchange system, a contact bank. multiple terminals of calling subscribers lilies `arranged therein in groups and sub-groups. a multi-position switch, means to position said switch in accordance. with the group designation of a calling line` registering apparatus, means to actuate said registering apparatus in accordance with the sub-group designation of said calling line, an automatic switch, means to advance said automatic switch in a group selecting movement under the control of said multi-position switch. said multi-position switch being advanced in response to movement of said automatic switch. means to advance said automatic switch in a sub-group selecting movement under the control of said multi-position switch in accordance with the setting of said registering apparatus. and means to advance said automatic switch into engagement with the terminals oi' the calling line.

lu a calldistributiug s vsiem` a pluralityY of operators positions. a contact bank divided into sections. eachsection containing multiple terminals of calling subscribers lines, a plurality of line finders serving each of said sections. means to extend a callin(r line to an operators position, means to render the selectability of an operators 'position dependent on .the number of unanswered calls present at such position, means controllable at said operators position to start an idle line tinder having access to the section in which the call originated, and means to operate said line tinder to establish connection to a calling line.

7. In a call distributing system, a plurality of operators positions, a Contact bank divided into sections, each section containing multiple terminals of calling subscribers lines, a plurality of line finders arranged toy serve each of said sections, said line linders being arranged in groups, there being as many groups as there are operators` positions, means to select an idle operators position in response to the initiation ot' a call, means operative thereupon to start a line finder in the group which has access to such idle operators position and which serves the section of contact bank in which the terminals of the calling line appear, and means to advance said line finder into engagement with the terminals of the calling line.

8. In a call distributing system, a plurality of operators positions, a contact bank' divided into sections, each section containin f multiple terminals of calling subscribers lines, a plurality of line finders arranged to serve each of said sections, said line iinders being arranged in groups, there being as many groups as there are operatorspositions, allotter switches associated lwith each operators position, there being as many allotter switches at each position as there are sections of contact bank, each allotter being arranged to determine which line finder of a group shall be started, means to select an operators position in response to the initiation of a call, `means operative thereupon to start a line finder in the group which has access to such idle operators position and which serves the section of contact bank in which the terminals of the calling line appear, and means to advance said line finder into engagement with the terminals of a callin r line.

9. n a call distributing system, a plurallll ity of operators positions, a contact bank ators position in response to the initiation of a call. means operative to said selection to start an allotted line finder in the group which has access to such idle operators pos1- tion, means to advance said line finder switch in group and sub-group selecting movements under the control of an asso-` ciated registering and sending equipment,

and means to advance said line finder into ixgagement with the terminals of the calling 10. In a tele hone exchange system, calling subscribers? lines, a pluralit of o ratol's positions, means to exten a line to a selectable o rs `tion, a counting device at sai o s position, meaim to actuate said counting device to record the number of unanswered calls present at said operators position at a time, and means to lender an rators position nonselectable after a pregtermined number of e hf: www@ n 1 a e one system, ing subscribers lines, a plurality of operators positions, means to extend a calling line to a selectable operators ition, means to render an opcrators v :'t1on non-selectable after two 68H8 lmvel :n exiinded tlllt,

Ameans to maintain said position non-selectable while two unanswered calls appear at lsition, one set of count' said position, or while one unanswered call is present and said operator is listening in on a second call, and means to render said position again selecta-ble `when one call only appears at said ition.Y p

12. In a telepliisne exchange system, calling subscribers lines, a plurality of operators positions, means to extend a calling line to a selectable operators position, a controlling relay, a pluralitv of sets of counting relays at each operatorls position, means to actuate said countin relays to record the number of nnanswere calls at an operators porelays being actu# ated for each unanswe call, means to ac- 'tnate said controlling relay when a predeterminedrnumber of said sets of count relays are actuated, and means controllle by said controlling relay to render the operators position non-selectable.

In witne whereof I hereunto subscribe my name this 27th day of March, A. D.

SAMUEL B` WILLIAMS, Jn. 

